1. Field of the Invention
The present invention relates to an ornament adapted to be fixed by means of a permanent magnet and, more particularly, to an ornament in which a rare earth-cobalt magnet or magnets are embedded in an ornament piece and/or in a cooperative attracting piece, wherein the magnetic attracting force is so selected to fall within a range of between 30 grams and 100 grams per square centimeter of the attaching area of the ornament body and, at the same, to be larger than 30 grams per gram of weight of the same.
2. Description of the Prior Art
Earrings are known as such a kind of ornament as having gems or the like attached to earlobes. Hitherto, three types of earrings have been used. More specifically, a first type of earrings has as shown in FIG. 1A, an ornament piece 1, an U-shaped adapter 2 and a cramp 3. This type of earring is attached to the earlobe by elastically cramping the latter by a cooperation of the U-shaped adapter 2 and the cramp 3.
FIG. 1B shows a second type of the conventional earrings having an ornament piece 1, U-shaped adapter 2 and a screw 4. The screw 4 and the U-shaped adapter 2 cooperate such that they cramp the earlobe when the screw 4 is driven deeper into the bore of the adapter 2 toward the earlobe.
A third type of conventional earrings has, as shown in FIG. 1C, a pin 5 to which an ornament piece 1 is fixed and a pin cramp 6. For attaching this type of earrings, the earlobe is previously pierced to form a small bore through which the pin 5 is inserted and retained by the pin cramp 6 at the back side of the earlobe.
Concerning the earrings as shown in FIGS. 1A and 1B, it is preferred to make the U-shaped adapters 2 invisible. Therefore, the constructions of the earring as shown in FIG. 1A and 1B are suitable for use in holding relatively large ornament pieces, rather than small-sized ornaments. The earring construction as shown in FIG. 1C requires the piercing of the earlobes, which has to be made only by skilled and authorized hands, although it may be suitably used for holding small-sized ornament pieces.
In order to overcome these disadvantages of the conventional three types of earrings, an idea of fixing the earrings to earlobes by means of magnets has been proposed for some time.
This way of fixing of the earrings is to make use of permanent magnets in both the ornament piece put on the front side of the lobe and the iron piece put on the back side of the lobe, so that they may be held on the lobe by the magnetic force which acts across the lobe.
However, unfortunately, conventional magnets such as alnico or ferrite magnet cannot provide a magnetic force across the earlobe, which is usually 2.5 to 3.0 mm thick, large enough to hold the pieces on the lobe.
More specifically, although the alnico magnet has a relatively large maximum value of the energy product of 10.times.10.sup.6 gauss oersted, this advantage cannot be efficiently made use of when the alnico magnet is used as the fixing means for earrings, because the alnico magnet has a vertically elongated form of its hysteresis loop. Namely, assuming here two disk-shaped magnets of 5 mm diameter and 1 mm thickness magnetized in the thicknesswise direction (This magnet will be referred to as 5.phi..times.1 magnet, hereinafter), the magnetic force acting between these magnets spaced by 2.5 mm is as small as about 0.8 grams.
The ferrite magnet is more advantageous in designing the 5.phi..times.1 magnets, although it has a relatively small maximum value of an energy product of 4.times.10.sup.6 gauss oersted. Thus, in case of the ferrite magnet, the magnetic force acting between the two 5.phi..times.1 magnets is about 3 grams.
However, the magnetic attracting force of the ferrite magnet of 3 grams is too small to securely hold the ornament on the earlobe against a usual movement of the user.
Recently, rare earth-cobalt magnets have been successfully developed, which conveniently have a large value of an energy product of 26.times.10.sup.6 gauss oersted, and a hysteresis characteristic similar to that of the ferrite magnet. It has been confirmed that the magnetic attracting force acting between two 5.phi..times.1 rare earth-cobalt magnets is as large as 14 grams, when these magnets are spaced by 2.5 mm from each other. This naturally triggered the desire to put the earrings fixed by permanent magnets into practical use.